FIG. 1 depicts a current semiconductor package 10. The semiconductor package 10 is a flip-chip package. The semiconductor package 10 includes a semiconductor die 12 on a ceramic base 14. The semiconductor package 10 is termed a flip-chip package because the top face of the die 10 is facing the ceramic base 14. Thus, contact is made to circuits within the die 12 through solder bumps 16. An underfill 18 is also included in the semiconductor package 10 and aids in bonding the die 12 to the ceramic base 14. The ceramic base 14 typically has a layer of metal 15 close to the top surface of the ceramic base 14. The ceramic base 14 is coupled to pins 19 which allow the die 12 to be electrically coupled to an outside circuit (not shown).
Although the semiconductor package 10 function when formed properly, current processing methods for semiconductor packages 10 typically does not result in all dies 12 functioning as desired. It is relatively simple to determine the failure mode, such as whether there is a short in a circuit within the die 12 or whether a particular voltage is being output. However, in order to determine the failure mechanism, the location and nature of the fault, the die 12 must be removed from the semiconductor package 10. In particular, the die 12 must be separated from the ceramic base 14. The die 12 can then be deprocessed and the failure mechanism determined.
FIGS. 2A and 2B depict a conventional system 20 and method 30 for removing the die 12 from the semiconductor package 10. Referring to FIGS. 2A and 2B, the die 12 is thinned, typically to between fifty and eighty microns, and a second die 22 is glued to the thinned die 12, via step 32. The second die 22 is typically a piece of silicon without any circuitry and of approximately the same size as the die 12. Generally, the ceramic base 14 is also trimmed to a certain extent. The combination of the thinned die 12, the second die 22 and the ceramic base 14 is then encapsulated in resin 24, via step 34. FIG. 2A depicts the thinned die 12, the ceramic base 14 and the second die 22 after being encapsulated in the resin 24. Typically, the encapsulation step 34 is carried out so that the ceramic base 14 is exposed. For example, the thinned die 12, the ceramic base 14 and the second die 22 may be placed in a mold with the ceramic base 14 down. The mold is then filled with resin and, after the resin has cured, removed from the mold. The ceramic base 14 is then ground until the die 12 has been exposed, via step 36. Typically, the grinding step is accomplished by mechanically grinding the ceramic base, and any resin 24 surrounding the ceramic base 14.
Although the method 30 functions, one of ordinary skill in the art will readily recognize that the die 12 typically cannot be removed from the resin 24. Currently, no known solvent will etch the resin 24 without damaging the die 12. Consequently, although the die 12 can be separated from the ceramic base 14, the die 12 cannot be easily deprocessed. Consequently, it is difficult, if not impossible, to determine a failure mechanism for the die 12 when the method 30 is used.
FIGS. 3A and 3B depict another conventional system 40 and method 50 for removing a die 12 from the semiconductor package 10. The die 12 is thinned and, if desired, glued to a second die (not shown), via step 52. The die 12 and ceramic base 14 are then fixed in a sample holder using a soft wax, via step 54. FIG. 3A depicts a sample holder 42 and the soft wax 44 which holds the die 12 and ceramic 14 in place. The soft wax 44 is typically somewhat pliable at room temperature. Note that the sample holder 42 need not have a recess which contains the soft wax 44, die 12 and ceramic base 14. Instead, the sample holder 42 may simply have a planar surface. The soft wax then simply affixes the die 12 and ceramic base 14 to the planar surface of the sample holder 42. The ceramic base 14 is then ground away to expose the die 12, via step 56. Typically, the ceramic base 14 is mechanically ground. The die 12 is then removed from the soft wax 44, by heating up the sample holder 42 and melting the soft wax 44.
Although the method 50 may separate the die 12 from the ceramic base 14, one of ordinary skill in the art will readily recognize that the method 50 is subject to failure. In particular, the die 12 often breaks during grinding of the ceramic base 14. For example, when the ceramic base 14 becomes very thin, the layer of metal 15 within the ceramic base 14 often fractures, breaking the remainder of the ceramic base 14 and the die 12. Furthermore, grinding heats the die 12 and ceramic base 14. As a result, the soft wax 44 softens further. This allows the die 12 and ceramic base 14 to move within the sample holder 42 during grinding. Consequently, the ceramic base 14 and die 12 are subject to breakage. Once the die 12 breaks, it becomes difficult if not impossible to deprocess the die 12. Consequently, failure mechanisms within the die 12 cannot be determined.
Accordingly, what is needed is a system and method for removing a semiconductor die from a semiconductor package. The present invention addresses such a need.